What is a stair tread calculator?

A stair tread calculator helps you calculate the exact tread depth and count for a staircase, ensuring safety and proper spacing.

How do I calculate stair tread size?

Enter the total rise and number of steps into the stair tread calculator, and it will compute the correct tread depth automatically.

Why is tread size important?

The tread size affects the comfort and safety of stair use. Proper tread sizing ensures stability and balance when climbing or descending stairs.

Stair Tread Calculator

Enter your measurements and preferences. This calculator supports Metric and Imperial units, suggests tread depth using Blondel's rule (2×rise + tread ≈ 630 mm / 25 in) and shows a scaled side-view preview.

Units

Total rise (floor to floor)

Enter the full vertical height between floors.

Desired riser height (suggested: 175–200 mm / 7–8 in)

Desired tread (run) depth (optional)

If left blank the calculator will suggest a tread using Blondel's rule.

Nosing (overhang) (optional)

Maximum riser height (safety limit)

Notes:

Blondel's rule: 2 × riser + tread ≈ 630 mm (25 in) — use as a guide, not a strict code requirement.
Check local building code for exact limits (maximum riser, minimum tread, handrail requirements).

Results

Computed risers

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Actual riser height

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Tread (run) depth

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Nosing

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Total run

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Stair angle

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Stair Tread Calculator

Results

Scaled side-view preview

Export / Actions